1. Field of the Invention
The present invention relates to a spot welding system for spot-welding a workpiece automatically by using a robot.
2. Description of the Related Art
When a workpiece is spot-welded automatically by using a robot, if a workpiece position recorded in a working program deviates from an actual workpiece position, problems such that an overload is applied to the workpiece and welding current does not properly flow may occur, which results in degradation of welding quality. Consequently, in the conventional art, the workpiece position is checked before spot-welding, and if the workpiece position is deviated, the workpiece position stored in the working program is corrected.
In a system described in Japanese Unexamined Patent Publication (kokai) No. 2008-132525 (JP2008-132525A), in place of a movable electrode, an imaging device is attached to a spot welding gun, so that the imaging device captures an image of the workpiece, and then a distance from the imaging device to the workpiece is computed. Then, based on the workpiece position information, the imaging distance and the like, the position correction is performed.
However, in the system described in JP2008-132525A, because complicated operations such as attachment and detachment of the imaging device, are required every time the position correction is carried out, the position correction cannot be quickly carried out.